package com.huobao.yunying.utils;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;

public class BitmapTools {

	public static Bitmap createImageThumbnail(String filePath){
		 Bitmap bitmap = null;
		 BitmapFactory.Options opts = new BitmapFactory.Options();
		 opts.inJustDecodeBounds = true;
		 BitmapFactory.decodeFile(filePath, opts);

		 opts.inSampleSize = computeSampleSize(opts, -1, 512*512);
		 opts.inJustDecodeBounds = false;

		 try {
			 bitmap = BitmapFactory.decodeFile(filePath, opts);
		 }catch (Throwable e) {
		}
		return bitmap;
	}

	public static int computeSampleSize(BitmapFactory.Options options, int minSideLength, int maxNumOfPixels) {
	    int initialSize = computeInitialSampleSize(options, minSideLength, maxNumOfPixels);
	    int roundedSize;
	    if (initialSize <= 8) {
	        roundedSize = 1;
	        while (roundedSize < initialSize) {
	            roundedSize <<= 1;
	        }
	    } else {
	        roundedSize = (initialSize + 7) / 8 * 8;
	    }
	    return roundedSize;
	}

	private static int computeInitialSampleSize(BitmapFactory.Options options,int minSideLength, int maxNumOfPixels) {
	    double w = options.outWidth;
	    double h = options.outHeight;
	    int lowerBound = (maxNumOfPixels == -1) ? 1 : (int) Math.ceil(Math.sqrt(w * h / maxNumOfPixels));
	    int upperBound = (minSideLength == -1) ? 128 :(int) Math.min(Math.floor(w / minSideLength), Math.floor(h / minSideLength));
	    if (upperBound < lowerBound) {
	        // return the larger one when there is no overlapping zone.
	        return lowerBound;
	    }
	    if ((maxNumOfPixels == -1) && (minSideLength == -1)) {
	        return 1;
	    } else if (minSideLength == -1) {
	        return lowerBound;
	    } else {
	        return upperBound;
	    }
	}
}
